Thank you Richard!

We did some quick measurements on material available for laboratory use
(FLUKA, Switzerland) and on caffeine extracted from coffee (13C only). The
results are more or less consistent with yours:

        FLUKA:          -40.5
        Natural:        -30.2

Our objective mainly is to discriminate medical preparations from natural
material. Very encouraging!

Best ...

        Uli Flenker
        Institute of Biochemistry
        German Sports University Cologne
        Carl-Diem-Weg 6

        50933 Cologne / Germany

        Phone 0049/0221/4982-493


On Tue, 16 Jan 2001, Richard Anderson wrote:

> Dear Uli,
>
> For what it's worth - We haven't done an exhaustive study of natural
> caffeines but we have had the chance to look at a few natural vs synthetic
> products from the US, India and China.  There's no mistaking the synthetic
> versions.
>
> Sample            Carbon            Nitrogen
> -----------------------------------------------------------
> USA syn           -37.2               -29.7
> USA nat            -27.0                 4.5
>
> India ?               -29.7                  1.5
> India nat            -29.7                  1.4
> India syn            -41.6              -29.1
>
> China ?             -33.7               -24.7
> China ?             -37.9               -13.9
> -----------------------------------------------------------
>
> Samples with "?" were labelled by country of origin but not for natural vs
> synthetic. If you are only interested in the natural products, the
> indication is that there may be some significant variations out there.
>
> Best regards,
> Richard Anderson